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• <br />use as standard practice for <br />conservation development planning. <br />This provides both ecological as well as <br />economic benefits. <br />Stormwater Treatment Train <br />The stormwater treatment is an approach to stormwater management <br />that relies on passive, overland routing of runoff as opposed to storm sewers <br />and other built structures. This approach offers a couple of distinct advantag <br />over conventional storm sewer systems: <br />1) Treatment of introduced contaminants picked up by runoff is removed at <br />the initial stages of water flowage rather than being transported to <br />downstream locations and accumulating in wetland and lake systems. This <br />greatly reduces degradation to water quality and vegetative health in <br />downstream systems. <br />2) Stormwater flow rates and volumes more closely emulate natural <br />conditions. This greatly reduces unnatural fluctuations in water levels in <br />downstream systems (wetlands and lakes) and therefore reduces impacts <br />to the natural condition of water systems and vegetation. <br />Treatment train systems typically consist of a four key components, each of <br />which perform in sequence to treat the water before it enters central weflands <br />and lakes. Initially, stormwater runoff from the built environment is routed <br />into swales planted with native prairie and wetland vegetation. These swales <br />convey runoff from built up areas into expansive prairies while also providing <br />a modest amount of infiltration and setting of solids. The prairies are the <br />second component of the treatment train, where they serve to slowly convey <br />Stormwater as diffuse overland flow to the wetland systems bordering <br />wetlands or lakes. The prairies infiltrate a substantial portion of the annual <br />surface runoff volume due to their very deep root system. They also provide <br />additional solids settling and biological treatment. The wetlands are the third <br />component of the treatment train system and provide both stormwater <br />detention and biological treatment prior to runoff entering the lake. The final <br />treatment component is the lake, which provides stormwater detention, <br />additional solids settling and biological treatment. Figure 7.5 illustrates the <br />treatment train system. <br />Stormwater Treatment Train <br />Figure 7.6 - Annual hydrograph comparison. <br />With respect to stormwater flow rates <br />• Page 5 <br />